M620 & u/seat exhaust

[bradders]

am I restricted in the same way with my new bike as I was the old one in having underseat exhaust, i.e. limited space around the shock? Part of me likes the idea of a single on the side, but underseat tucks it away so minor offs wont touch the can...or that';s the thinking anyway!

[Chaz]

am I restricted in the same way with my new bike as I was the old one in having underseat exhaust, i.e. limited space around the shock? Part of me likes the idea of a single on the side, but underseat tucks it away so minor offs wont touch the can...or that';s the thinking anyway!

The monster frame dosn't lend itself to fit under seat exhaust Paul no room to get it round the swinging arm & shock.

[bradders]

thx chaz as I thought, will likely be similar set up to your old ones and steve masons then; light as poss can.

Did you use std headers & adapt or go larger? Also what size can - e.g. 50mm? Will probably sell the high level ones fitted to recoup some of the cost so wont be using those and need to find one, thinking an old R6 or ZXR type thing should do..

[bradders]

was thinking something like this

http://www.ebay.co.uk/itm/Kawasaki-ZX-ZX10R-ZX-10R-MOTO-GP-STUBBY-RACE-CAN-EXHAUST-SILENCER-/130603078897?pt=UK_Motorcycle_Parts&hash=item1e688cd4f1#ht_500wt_949

[skidlids]

was thinking something like this

http://www.ebay.co.uk/itm/Kawasaki-ZX-ZX10R-ZX-10R-MOTO-GP-STUBBY-RACE-CAN-EXHAUST-SILENCER-/130603078897?pt=UK_Motorcycle_Parts&hash=item1e688cd4f1#ht_500wt_949

But will it pass the ACU noise Tests that are run at all MSV circuits as well as many of the others
I wonder if MTC give it a dB rating

[bradders]

just stick a baffle in cant I? Or add a load of wadding? Obviously I wouldn't want to restrict the flow too much, defeats the object!

Dont you run an R6 on yours Kev? I'd like a smaller can to make it nice and tidy but wouldn't want to run foul of the rules!

This is the look I'd love to achieve if poss, or close to, if I cant realistically go u'seat:

http://i333.photobucket.com/albums/m399/paul-bradbury/radical-ducati-corsa.jpg

[Ghost]

Rons was a monster and his underseat system looked and worked ok.

[bradders]

Rons was a monster and his underseat system looked and worked ok.

but as he said many times it was down on power ;)

the space where the pipes go up thru the shock is very limited and if you looked at his, it had one side much larger than the other. Take a lot of dyno work, messing around and cash to sort that right unless someone got lucky

the M620 doesnt have a hoop tho and I know you can fit a 916 shock so just wondered if there was more space, not got the bike home yet so cant just go have a look, but seems those that know think not

[NBs996]

It's already got a 996 shock fitted Bradders, so that's consumed a bit of space already unless you want the standard shock on there?
Anyway, what's up with the pipes on it already?

[bradders]

yeah I know Nick, wasn't sure if it took space or made it. As is please ;)

less weight and no chance of fouling my heels...and I want to make it 'my own' :)

intending it will be my track bike after racing, so think spending the money to get it right now is a worthwhile thing

[skidlids]

Ron's Monster was the earlier type with the suspension loop, the 620 setup which is pretty much the same as 748/916 749/999 with its tie rod leaves even less room to get the pipework through, you would need to run it around the side like the 749/999 but the double sided arm isn't designed for it.

My can is a Harris can made for the stsyems they used on the GSXR750s they ran in World Superbike. The can itself is about 16" long.

Around 1996/97 the Noise regs changed to there current level of 105dB, one year everybody was using 14" cans the next they had all grown a couple of Inches. So getting a free flowing can to meet 105dB and getting the size down to 10" probably isn't going to happen. Reducing the diameter with a baffle will reduce the noise as it reduces the Gas flow.
Using a baffle for sound testing and then removing it for racing is basically cheating. When others are using a bike with a exhaust that restricts the noise level to 105dB it also has implications on the power available, so anybody using a free'r flowing exhaust making more than 105dB is not playing by the same rule book.

[bradders]

how big do you reckon then? And what size diameter Kev?

I'd guess Craig's weren't an issue because he had 2?

[Cranker V2]

im going to use an akrapovic like this with custom link pipe. Short, neat and tucked away - bit like my nads most of the season:confused:

http://www.ebay.co.uk/itm/AKRAPOVIC-MEGAFON-SLIP-MOTO-GP-CAN-TITANIUM-R6-2006-/270861141423?pt=UK_Motorcycle_Parts&hash=item3f109505af

[skidlids]

That wont pass noise testing, just like the Laser dual cans for a R6 that Dallas got for his bike last week,

http://www.ebay.co.uk/itm/Yamaha-R6-Exhaust-Laser-X-treme-Gp-Style-2006-2007-2008-2009-06-07-08-09-/260901342503?pt=UK_Motorcycle_Parts&hash=item3cbeee8d27

nothing in them as a lot of the silencing done on an R6 is in the exhaust collector system hidden away under the engine and out of site behind the fairing.

http://www.ebay.co.uk/itm/YAMAHA-YZF-R6-2CO-2006-2007-HEADERS-DOWNPIPES-CAT-EXHAUST-SYSTEM-FRONT-PIPE-/330636957647?pt=UK_Motorcycle_Parts&hash=item4cfb7f97cf

He's going to get Austin Racing build him one, probably like the one he had on the RSV4 where you fit different inserts for diffent dB levels

A earlier R6 Silencer would be a better option
http://www.ebay.co.uk/itm/GP-Style-Exhaust-YAMAHA-YZF-R6-R-6-99-02-EX100-/150609502796?pt=UK_Motorcycle_Parts&hash=item231106a24c

[skidlids]

how big do you reckon then? And what size diameter Kev?

I'd guess Craig's weren't an issue because he had 2?

50mm (2") core 16" long has been the norm for some time

Craig as you say has two cans that are linked so probably has nearer to 20 inches of silencing. Which is more than my bike has which when last checked at Oulton mine recorded 101.5dB. So its gone up by around 2dB over the season, soon be time to strip it down and repack it

Here are the MSV regs on Noise levels for their circuits
http://www.clubmsv.com/bike-testing-noise-limits.aspx

[bally71]

Don't know if you guys have seen this before

http://www.mez.co.uk/mezporting/exhaust_length.html

[bradders]

Don't know if you guys have seen this before

http://www.mez.co.uk/mezporting/exhaust_length.html


ooo new website to baffle me! How does that work???

cheers Kev, I'll weigh up whether i'm better using what I have or selling them and getting another.

[skidlids]

Don't know if you guys have seen this before

http://www.mez.co.uk/mezporting/exhaust_length.html

I was in their neck of the woods 2 weeks ago, they use to do my mate Marios (Maz) 906 Paso that he Drag Raced in the Supertwins class many years ago

[skidlids]

cheers Kev, I'll weigh up whether i'm better using what I have or selling them and getting another.

My 620 Monsters got standard system so thats got to go, i've decided to go with a 2 into 1 similar to my 620SS

May see about getting one of my 2 into 1 conversions modified but in the short term I bought a S2R decat pipe earlier today for £29 and will see If I can use that. Already having one on my S2R out in the garage it LOOKS like its a possibility

[Jolley]

but as he said many times it was down on power ;)

the space where the pipes go up thru the shock is very limited and if you looked at his, it had one side much larger than the other. Take a lot of dyno work, messing around and cash to sort that right unless someone got lucky

the M620 doesnt have a hoop tho and I know you can fit a 916 shock so just wondered if there was more space, not got the bike home yet so cant just go have a look, but seems those that know think not

Paul, you could definitely do underseat, and it would work. It looks the nuts and saves a lot of work in an off (of which I had too many). My old B bike had 50-51bhp with the single side exhaust and went down to 48-49 with the underseat and rebuild. However, it isn't that straight forward. I have no direct comparison to the two exhausts with exactly the same motor. In addition, bhp isn't the whole story. Torque is the pulling power, and mine definitely pulled (at times) as well as Senna/Sorted/Ghost/Hugh's bikes, who were all amongst the strongest engines. With (only) 65bhp you should be able to get an underseat exhaust made up to expel the gases fast enough.

I don't see how it would be any harder than on my B bike... the front pipe came under the engine and through the swingarm, then connected with a short pipe from the rear cylinder before meeting the silencer. I don't see why that couldn't be done on a 620. The main technical "problem" with this set-up is that to keep a nice balanced motor the theory states that you should have equal length headers that provide the same flow/backpressure to each cylinder. Obviously this is impossible.

[bradders]

Agree Ron, look so much neater and less to damage - and I'm likely to ;) - I think technically there may be even less space, like I say I don't have one to check at the mo, so as Kev said its probably outside of the subframe as Badger

To get the flow equal, from what I have read you need to have either the same length pipes or one larger than the other to compensate. Which I think yours did if I recall as it went past the hoop.

[Spjallen]

A wise man told me that you should think at the pipework as volume not length. A short fat pipe will be equal in volume to a long thin one.

[bradders]

bit like me versus Hugh? PMSL

[bradders]

A wise man told me that you should think at the pipework as volume not length. A short fat pipe will be equal in volume to a long thin one.

hopefully they'll have yours as a template for mine :D

[skidlids]

Paul, you could definitely do underseat, and it would work. It looks the nuts and saves a lot of work in an off (of which I had too many)..

In the 7 seasons of DD I've had a few offs as has Kev P and I can't recall either of us having to replace an exhaust, mine has always been side mounted, started with a Micron can off my CBR6 and then fitted the Harris Can and put the Micron back on the CBR6
Kev P had underseat exhausts for the first two seasons but has run side mounted pipes since then.
Dallas has also had a few crashes and the only time I remember him damaging an Exhaust was in his big crash at Pembrey hairpin when the Brake Disc exploded, the exhaust from that crash is still useable unlike a lot of the bike.

I suppose costs need considering, side mounted cans are easy to pick up secondhand and fairly cheap, so easy enough and cheap enough to carry a spare. Undeseat exhausts are usually bespoke systems that cost a few hundred quid to get made and often they are compromised by the space and gaps available for routing them. Add to that they must weigh more as extra pipework is required and that weight is rear biased.

Certainly works in opposition to fitting a lighter fuel tank, as in take a couple of Kilos off the front and add a chunk of that saving to the rear, go figure

[bradders]

only one I can remember destroying a can was that Ali geezer at the Doom, and he took 3 good goes at it till he got it right!!

[bradders]

Certainly works in opposition to fitting a lighter fuel tank, as in take a couple of Kilos off the front and add a chunk of that saving to the rear, go figure

and weight is important...and better to keep weight low to the ground isn't it?! altho I cant have my shortyy can :(

[Cranker V2]

Sure ley a can thats meets the required 105dB limit is all that is required, whether it be long or short............

[bradders]

Sure ley a can thats meets the required 105dB limit is all that is required, whether it be long or short............

think skids is saying it wont. Answer maybe get a 2nd hand one off ebay, fit it, test it and if no good change to a longer one

[Cranker V2]

my 50mm standard length (?) carbon race can was measuring 98 db all last season.

[skidlids]

and weight is important...and better to keep weight low to the ground isn't it?! altho I cant have my shortyy can :(

Some people don't mind a high centre of gravity as the bike rops on to its side easier, just takes more physical effort to pick it back up, so things like chicanes become harder work, especially towards the end of a long race at the end of a long weekend.

Throughout the Moto GP era there has been a real focus of getting the centre of gravity in the right place and centralising the weight. As nobody likes to much weight seesawing back and forth


As for Silencers your trying to dissipate a fast moving sound wave, fast as in travelling at the speed of sound, so how do you get it to dissipate enough before it reaches the sound meter. I would go for giving it a fairly long not to restrictive baffle say 450mm long with 50mm diameter as the alternative is a short restrictive one say 200mm long and 35mm diameter, equivalent to some of these so called race cans with a dB killer fitted

The Austin Racing system on the RSV4 I had off Dallas is quoted as
102/103 with 35mm insert 104/105 with 50mm inserts and 108dB without and thats all with a new silencer and where the insert drops in to the link pipe prior to the silencer. So if you want to insure you pass the Noise test you would probably have to be running with the 35mm insert all of the time .

Be my guest to run what yo want, but you'll probably end up in the race office complaining that you failed just like one guy did at the Final Hottrax meeting at Snetterton 200. When the only way to get his R6 through was to fit a dB killer

I helped Sound Check 40 bikes that weekend and they ranged from 98 dB up to 105dB on our record sheet. Hopefully those that were right on the limit will be repacked over the winter ready for next season

[chris.p]

One other thing to remember when choosing the length/diameter of a can is what it does to the performance of the bike.

By changing the internal diameter of the pipe and/ or the length of the pipe will effect the bhp and torque curves of your bike.

Shorter pipes give more top end at the expense of mid range and visa verser.

What may look good and cool on the bike could be robbing you of power where you need it most.



Chris:burn:

[bradders]

One other thing to remember when choosing the length/diameter of a can is what it does to the performance of the bike.

By changing the internal diameter of the pipe and/ or the length of the pipe will effect the bhp and torque curves of your bike.

Shorter pipes give more top end at the expense of mid range and visa verser.

What may look good and cool on the bike could be robbing you of power where you need it most.



Chris:burn:

good point Chris, I remember Senna saying he changed his at the dyno as the slightly longer cans gave a bit more oomph

[skidlids]

Longer ones usually give it a bit less, in Kev's Case I think the Contis worked out as a longer internal silencer than the exhausts he changed to

Did the same with Dallas 2010 Class A bike, had to fit a longer can to drop the BHP a bit to get it within the class limit, but gained some midrange from the change